Ventilation duct plug



FIG. 1 is a perspective view of a ventilation duct plug comprising the new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevation view thereof, the rear elevation view being a mirror image thereof:

FIG. 4 is a left end view thereof, the right end view being a mirror image thereof;

FIG. 5 is a top perspective of the design shown in FIGS. 1-4 in a different environment, having a filtering medium shown in broken lines; and,

FIG. 6 is a bottom perspective view thereof.

The dashed lines that appear in FIGS. 1 through 6 illustrate environment only and form no part of the claimed design. 

CLAIM The ornamental design for a ventilation duct plug, as shown and described. 